The present invention generally relates to a nozzle head, and in particular to a nozzle head of a type having a nozzle carrier supported for rotation about a longitudinal axis and driven by a recoil action caused by pressurized water exiting spray nozzles accommodated in the nozzle carrier, and a stationary housing provided with an inlet for pressurized water and rotatably supporting a hollow shaft which is secured to the nozzle carrier and has a central passage for conducting pressurized water from the inlet to the spray nozzles.
German patent publication DE 38 27 251 A1 discloses a nozzle head of this type, with pressurized water being conducted from the inlet via a sleeve, which extends in an expanded bore in the hollow shaft, to the spray nozzles of the nozzle carrier. Formed between the sleeve and the boundary surface of the expanded bore of the hollow shaft is a labyrinth gap seal formed by circular grooves spaced on the periphery of the sleeve. Despite the provision of the labyrinth gap seal, leakage water, i.e. a partial amount of the pressure medium flows between the sleeve and the hollow shaft and is received in a chamber which is formed with radially outwardly extending discharge bores. A drawback of this conventional nozzle head is the fact that the sleeve is subject to wear and must be replaced periodically.